In optical communications, optical signals carry information. For example, a transmitter (e.g., a laser or laser diode) in an optical or optoelectronic transceiver converts one or more electrical signals into optical signals, and a receiver (e.g., a photodiode) in an optical or optoelectronic transceiver converts one or more optical signals into electrical signals. One objective of optical communication research and development is to increase and/or maximize bandwidth (e.g., the amount of information transmitted) to the greatest extent possible. Another objective is to communicate the information with as few errors or losses as possible.
In a number of conventional designs, the optics in an optical or optoelectronic receiver includes a mirror at a 45° angle relative to the incoming optical signal and a lens placed at a 90° angle relative to the incoming optical signal. The mirror reflects the incoming optical signal towards the lens, and the lens focuses the optical signal onto a photodetector. However, the lens and/or other components in the optical path of the incoming optical signal may reflect some of the light (e.g., back along the optical path). This reflected light can interfere with the incoming optical signal, and in the worst case, damage components of the receiver and/or network. Interference from reflected light can cause errors in signal processing and/or losses of data in the receiver.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.